This present invention relates to a device and method for speeding up the printing and reproduction of documents.
Today, high-speed reproduction devices such as copier-duplicator machines are capable of reproducing documents at over 100 pages per minute. The increased speed of the document reproduction process completes jobs faster to allow higher throughput, and productivity, and ultimately contributing to greater productivity and profitability for an operator as jobs are more handled more quickly and efficiently.
Limitations to the speed at which document reproduction can be increased, however, have been encountered. For example, a high-speed document reproduction process typically utilizes a flash lamp device such as Xenon lamps to illuminate the image to be reproduced. The flash device must illuminate the image at a rate according to the desired rate of reproduction. For example, a reproduction rate of 120 pages per minute requires a frame of the image be shot every 500 milliseconds. Accordingly, the flash device is synchronized to be actuated at the same 500-millisecond rate to properly illuminate the image for each shot.
Typically, these high illumination flash devices require substantial electrical energy to fire and provide the desired illumination often necessitating hundreds of joules of electrical energy to be generated. In fact, the energy of each flash is roughly equal to       1    2    ⁢      CV    2  
in watt-seconds (or joules), where C is the capacitance of an energy storage capacitor and V is the voltage across the energy storage capacitor. Thus, to generate enough energy to properly drive the flash device, a capacitor is preferably charged up to it a large voltage V generally requiring a significant amount of time to charge. As the document reproduction rate increases, however, the rate the flash device operates increases proportionally and accordingly the time available in between successive flashes for the power supply to generate the necessary power is reduced. If the reproduction rate and the corresponding flash rate become too great, the capacitor may not be able to generate the required energy in the available time before the flash is to fire. Consequently, the flash device will not have enough energy to adequately illuminate the image.
The embodiments described herein allow for increasing the rate of reproduction devices.
Addressing the problems with high-speed reproduction devices described above, the present embodiments provide the ability to increase the rate at which the printing of images and documents can take place. The exemplary embodiments disclose a system and method capable of extending the capacity of high-speed reproduction machines.
According to an aspect of the present invention, an illumination device is driven by two or more plurality energy sources. From a flash command synchronized to the document reproduction rate, a number of control signals may be generated to charge and actuate the energy sources with the proper timing and synchronization to drive the illumination device at the desired rate. In the exemplary embodiment, circuitry is provided to generate the necessary signals to control the energy sources from a single flash command.
According to another aspect of the invention, the energy sources are charged such that the charging of at least one energy source overlaps the charging of another energy source. Preferably, the energy sources can be synchronized to charge and fire in an alternating manner to drive the illumination device. The charge command is synchronized to the flash command to initiate charging of the energy sources at the appropriate timing to allow the energy sources sufficient time to charge to the voltage level necessary to properly fire the illumination device. In the exemplary embodiment, the charge command necessarily initiates the charging of at least one energy source while another energy source is already being charged.
The present invention provides a number of advantages and applications as will be more apparent to those skilled in the art. Utilizing the disclosed embodiments, the present invention allows document reproduction capacity and productivity to be increased. The exemplary embodiments utilize a plurality of energy sources charging simultaneously to increase the rate in which a flash illumination device can be fired.